The present invention relates to a rust inhibitor for metal. More particularly, the invention relates to a metal working fluid or water soluble rust inhibitor, which can be used for storing metallic parts.
A cutting fluid or lubricant is used for cutting metals such as an iron, aluminum, and various types of alloys. Such cutting fluid and lubricant is a water insoluble cutting oil, water soluble cutting oil, or water soluble composition developed by the inventors of the present invention. Generally, a rust inhibitor is added to these cutting fluids and lubricants to protect metal from corrosion.
The rust inhibitor can be used for various purposes. For example, it can also be used with a cooling fluid for radiators.
However, a conventional rust inhibitor has drawbacks of having toxicity and inferior rust resistance.
Accordingly, an object of the present invention is to provide a rust inhibitor having low toxicity so as not to adversely affect the environment.
Another object of the present invention is to provide a rust-inhibiting composition having high rust resistance.
As the result of our researches on the development of an environment-friendly rust inhibitor having high rust resistance, we have eventually found the present invention.
The rust inhibitor of the present invention is an aqueous solution containing saturated fatty acid, saturated dicarboxylic acid and salt thereof, chelating agent, tolyltriazole or benzotriazole, and fatty acid metal salt.
The rust inhibitor of the present invention may further contain hydroxide and/or methasilicate such as sodium methasilicate.
The rust inhibitor of the present invention may be an aqueous solution containing 0.1 to 5 wt % of saturated fatty acid, 0.01 to 1 wt % of saturated dicarboxylic acid and salt thereof, 0.01 to 1 wt % of chelating agent, 5xc3x9710xe2x88x923 wt % to 1 wt % of tolyltriazole or benzotriazole, and 0.01 to 1 wt % of fatty acid metal salt.
The saturated fatty acid can be at least one selected from the group consisting of caprylic acid, caproic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid.
The saturated dicarboxylic acid can be dodecanoic diacid or sebacic acid.
The chelating agent can be a derivative of ethylenediamine tetraacetic acid or a derivative of nitrilotriacetic acid.
The hydroxide can be potassium hydroxide. The concentration of the hydroxide can be in a range of 0.1 to 5 wt %.
The fatty acid metal salt can be fatty acid potassium salt.
A rust inhibitor of the present invention is an aqueous solution prepared by dissolving at least saturated fatty acid, saturated dicarboxylic acid and salt thereof, chelating agent, tolyltriazole or benzotriazole, and fatty acid metal salt in distilled water, deionized water, tap water or the like.
The rust inhibitor of the present invention can be prepared by further adding hydroxide and/or methasilicate.
Although the amounts of saturated fatty acid, saturated dicarboxylic acid and salt thereof, chelating agent, tolyltriazole or benzotriazole, and fatty acid metal salt are not particularly limited, the rust inhibitor of the present invention is an aqueous solution containing 0.1 to 5 wt % of saturated fatty acid, preferably 0.3 to 1 wt %; 0.01 to 1 wt % of saturated dicarboxylic acid and salt thereof, preferably 0.03 to 0.1 wt %; 0.01 to 1 wt % of chelating agent such as a derivative of ethylenediamine triacetic acid, preferably 0.02 to 0.1 wt %; 5xc3x9710xe2x88x923 to 1 wt % of tolyltriazole or benzotriazole, preferably 0.01 to 0.1 wt %; and 0.01 to 0.1 wt % of fatty acid metal salt, preferably 0.02 to 0.1 wt %.
The saturated fatty acid contained in the rust inhibitor of the present invention is not particularly limited, but any saturated fatty acid known to persons skilled in the art can be used. Preferable saturated fatty acid is at least one selected form the group consisting of caprylic acid, caproic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid.
The saturated dicarboxylic acid contained in the rust inhibitor of the present invention is not particularly limited, but any saturated dicarboxylic acid known to persons skilled in the art can be used. Preferable saturated dicarboxylic acid is dodecanoic diacid or sebacic acid.
The chelating agent contained in the rust inhibitor of the present invention is not particularly limited, but any chelating agent known to persons skilled in the art can be used. Examples of the chelating agent include a derivative of ethylenediamine tetraacetic acid or nitrilotriacetic acid. Preferable chelating agent can be ethylenediamine tetraacetate tetrasodium salt (EDTA-4Na4H2O) complex or the like.
The fatty acid metal salt contained in the rust inhibitor of the present invention is not particularly limited, but any fatty acid metal salt known to persons skilled in the art can be used. Examples of preferable fatty acid metal salt include fatty acid potassium salt, fatty acid sodium salt, and the like.
The aqueous solution prepared from saturated fatty acid, saturated dicarboxylic acid and salt thereof, chelating agent such as a derivative of ethylenediamine tetraacetic acid, tolyltriazole or benzotriazole, fatty acid metal salt can be used for various purposes as a substitute of a conventional rust inhibitor. However, in order to increase a rust resistance, the solution preferably further contains hydroxide or methasilicate as a pH adjuster. The hydroxide used herein is not particularly limited, but any hydroxide known to persons skilled in the art can be used. Examples of hydroxide include sodium hydroxide, potassium hydroxide, calcium hydroxide, and the like. The methasilicate used herein is also not particularly limited, but any methasilicate known to persons skilled in the art, such as sodium methasilicate, can be used.
In addition, the rust inhibitor of the present invention may further contain stabilizer and the like.
The rust inhibitor of the present invention can effectively protect various metals as iron, cupper, stainless steel, and aluminum from rust, so that it can be added to a metal cutting fluid to be used in metal cutting operation or can be used as an anticorrosive dye. In addition, the rust inhibitor of the present invention can be used as circulating water for radiator or air conditioner of a motor vehicle, or circulating fluid for floor heating.
The rust inhibitor of the present invention has lower toxicity than conventional rust inhibitors containing chrome and amine. Furthermore, the rust inhibitor of the present invention has high compatibility with a metal working fluid developed by the inventors of the present invention, and protects the metal from rust.
The rust inhibitor of the present invention will be more clearly understood by referring to the Examples below. However, the Examples should not be construed to limit the invention in any way. It will be apparent to those skilled in the art that various improvements, changes, and modifications can be made thereto without departing from the spirit or scope of the present invention.